Preparation

Server setup

You will need to setup a DHCP, TFTP, and HTTP server to configure networking, load pxelinux/kernel/initramfs, and finally load the root filesystem (respectively).

The Arch ISO currently only supports BIOS-style PXE booting. See FS#50188 for more information.

Arch Netboot does support UEFI-style booting if you require that. Rest of this page focuses on the ISO however.

Network

Bring up your wired NIC, and assign it an address appropriately.

# ip link set eth0 up
# ip addr add 192.168.0.1/24 dev eth0

DHCP + TFTP

You will need both a DHCP and TFTP server to configure networking on the install target and to facilitate the transfer of files between the PXE server and client; dnsmasq does both, and is extremely easy to set up.

HTTP

Thanks to recent changes in archiso, it is now possible to boot from HTTP (archiso_pxe_http initcpio hook) or NFS (archiso_pxe_nfs initcpio hook); among all alternatives, darkhttpd is by far the most trivial to setup (and the lightest-weight).

Note that it is important that the server is running on port 80. If you start darkhttpd without root access it will default to 8080. The client will try to access port 80 and the boot will fail.

Installation

For this portion you will need to figure out how to tell the client to attempt a PXE boot; in the corner of the screen along with the normal post messages, usually there will be some hint on which key to press to try PXE booting first. On an IBM x3650 F12 brings up a boot menu, the first option of which is Network; on a Dell PE 1950/2950 pressing F12 initiates PXE booting directly.

Boot

Looking at journald[broken link: invalid section] on the PXE server will provide some additional insight to what exactly is going on during the early stages of the PXE boot process:

# journalctl -u dnsmasq.service -f

dnsmasq-dhcp[2544]: DHCPDISCOVER(eth1) 00:1a:64:6a:a2:4d
dnsmasq-dhcp[2544]: DHCPOFFER(eth1) 192.168.0.110 00:1a:64:6a:a2:4d
dnsmasq-dhcp[2544]: DHCPREQUEST(eth1) 192.168.0.110 00:1a:64:6a:a2:4d
dnsmasq-dhcp[2544]: DHCPACK(eth1) 192.168.0.110 00:1a:64:6a:a2:4d
dnsmasq-tftp[2544]: sent /mnt/archiso/arch/boot/syslinux/pxelinux.0 to 192.168.0.110
dnsmasq-tftp[2544]: sent /mnt/archiso/arch/boot/syslinux/archiso.cfg to 192.168.0.110
dnsmasq-tftp[2544]: sent /mnt/archiso/arch/boot/syslinux/whichsys.c32 to 192.168.0.110
dnsmasq-tftp[2544]: sent /mnt/archiso/arch/boot/syslinux/archiso_pxe_choose.cfg to 192.168.0.110
dnsmasq-tftp[2544]: sent /mnt/archiso/arch/boot/syslinux/ifcpu64.c32 to 192.168.0.110
dnsmasq-tftp[2544]: sent /mnt/archiso/arch/boot/syslinux/archiso_pxe_both_inc.cfg to 192.168.0.110
dnsmasq-tftp[2544]: sent /mnt/archiso/arch/boot/syslinux/archiso_head.cfg to 192.168.0.110
dnsmasq-tftp[2544]: sent /mnt/archiso/arch/boot/syslinux/archiso_pxe32.cfg to 192.168.0.110
dnsmasq-tftp[2544]: sent /mnt/archiso/arch/boot/syslinux/archiso_pxe64.cfg to 192.168.0.110
dnsmasq-tftp[2544]: sent /mnt/archiso/arch/boot/syslinux/archiso_tail.cfg to 192.168.0.110
dnsmasq-tftp[2544]: sent /mnt/archiso/arch/boot/syslinux/vesamenu.c32 to 192.168.0.110
dnsmasq-tftp[2544]: sent /mnt/archiso/arch/boot/syslinux/splash.png to 192.168.0.110

After you load pxelinux.0 and archiso.cfg via TFTP, you will (hopefully) be presented with a syslinux boot menu with several options, where you can select Boot Arch Linux (x86_64) (HTTP).

Next the kernel and initramfs (appropriate for the architecture you selected) will be transferred, again via TFTP:

dnsmasq-tftp[2544]: sent /mnt/archiso/arch/boot/x86_64/vmlinuz to 192.168.0.110
dnsmasq-tftp[2544]: sent /mnt/archiso/arch/boot/x86_64/archiso.img to 192.168.0.110

If all goes well, you should then see activity on darkhttpd coming from the PXE-target; at this point the kernel would be loaded on the PXE-target, and in init:

After the root filesystem is downloaded via HTTP, you will eventually end up at the normal live system root zsh prompt.

Post-boot

Unless you want all traffic to be routed through your PXE server (which will not work anyway unless you set it up properly), you will want to stopdnsmasq.service and get a new lease on the install target, as appropriate for your network layout.

You can also kill darkhttpd; the target has already downloaded the root filesystem, so it is no longer needed. While you are at it, you can also unmount the installation image:

Alternate Methods

As implied in the syslinux menu, there are several other alternatives:

NFS

You will need to set up an NFS server with an export at the root of your mounted installation media, which would be /mnt/archiso if you followed #Preparation. After setting up the server, add the following line to your /etc/exports file:

/etc/exports

/mnt/archiso 192.168.0.0/24(ro,no_subtree_check)

If the server was already running, re-export the filesystems with exportfs -r -a -v.

The default settings in the installer expect to find the NFS at /run/archiso/bootmnt, so you will need to edit the boot options. To do this, press Tab on the appropriate boot menu choice and edit the archiso_nfs_srv option accordingly:

archiso_nfs_srv=${pxeserver}:/mnt/archiso

Alternatively, you can use /run/archiso/bootmnt for the entire process.

After the kernel loads, the Arch bootstrap image will copy the root filesystem via NFS to the booting host. This can take a little while. Once this completes, you should have a running system.

NBD

Existing PXE Server

If you have an existing PXE server with a PXELINUX system setup (e.g. a combination of DHCP and TFTP), you can add the following menu items to your pxelinux.cfg file in order to boot Arch via your preferred method:

You can replace archiso_http_srv with archiso_nfs_srv for NFS or archiso_nbd_srv for NBD. Adding the ip= instruction is necessary to instruct the kernel to bring up the network interface before it attempts to mount the installation medium over the network. See README.bootparams for available boot parameters.

Low memory systems

The copytoraminitramfs option can be used to control whether the root filesystem should be copied to ram in its entirety in early-boot.

It highly recommended to leave this option alone, and should only be disabled if entirely necessary (systems with less than ~256MB physical memory). Append copytoram=n to your kernel line if you wish to do so.

Note: As this requires loop-mounting squashfs from a mounted remote filesystem, copytoram=n and archiso_pxe_http are mutually exclusive.